U.S. patent application number 13/288156 was filed with the patent office on 2012-11-22 for image pickup device, digital photographing apparatus using the image pickup device, auto-focusing method, and computer-readable medium for performing the auto-focusing method.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Takafumi Usui.
Application Number | 20120293706 13/288156 |
Document ID | / |
Family ID | 47174681 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120293706 |
Kind Code |
A1 |
Usui; Takafumi |
November 22, 2012 |
IMAGE PICKUP DEVICE, DIGITAL PHOTOGRAPHING APPARATUS USING THE
IMAGE PICKUP DEVICE, AUTO-FOCUSING METHOD, AND COMPUTER-READABLE
MEDIUM FOR PERFORMING THE AUTO-FOCUSING METHOD
Abstract
An image pickup device is provided including a plurality of
pixels arranged over an entire region of the image pickup device,
each pixel including: a plurality of light-receiving sub-pixels
that generate an image pickup signal from incident light; and a
phase-difference detection sub-pixel having a confined
light-receiving region. The plurality of pixels includes first
group pixels and second group pixels that are each classified
according to an arrangement of the confined light-receiving region
of the phase-difference detection sub-pixel thereof, and the
confined light-receiving region of the phase-difference detection
sub-pixel of the first group pixels and the confined
light-receiving region of the phase-difference detection sub-pixel
in the second group pixels are arranged biased to opposite
directions.
Inventors: |
Usui; Takafumi; (Seoul,
KR) |
Assignee: |
Samsung Electronics Co.,
Ltd.
Suwon-si
KR
|
Family ID: |
47174681 |
Appl. No.: |
13/288156 |
Filed: |
November 3, 2011 |
Current U.S.
Class: |
348/345 ;
250/208.1; 348/E5.045 |
Current CPC
Class: |
H01L 27/14632 20130101;
H04N 5/23212 20130101; H04N 5/232122 20180801; H04N 9/04557
20180801; H04N 5/3696 20130101; H04N 5/335 20130101; H04N 5/232123
20180801; H04N 9/04515 20180801; H01L 27/14605 20130101; H04N
5/36961 20180801; H04N 9/045 20130101; H01L 27/14629 20130101 |
Class at
Publication: |
348/345 ;
250/208.1; 348/E05.045 |
International
Class: |
H04N 5/232 20060101
H04N005/232; H01L 27/146 20060101 H01L027/146 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2011 |
KR |
10-2011-0045682 |
Claims
1. An image pickup device comprising a plurality of pixels arranged
over an entire region of the image pickup device, each pixel
comprising: a plurality of light-receiving sub-pixels that generate
an image pickup signal from incident light; and a phase-difference
detection sub-pixel having a confined light-receiving region;
wherein the plurality of pixels comprises first group pixels and
second group pixels that are each classified according to an
arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof; and the confined
light-receiving region of the phase-difference detection sub-pixel
of the first group pixels and the confined light-receiving region
of the phase-difference detection sub-pixel in the second group
pixels are arranged biased to opposite directions.
2. The image pickup device of claim 1, wherein: the confined
light-receiving region of the first group pixels is arranged biased
to a first direction defined along a row direction; the confined
light-receiving region of the second group pixels is arranged
biased to a second direction opposite to the first direction; and
the first group pixels and the second group pixels are each
consecutively arranged in the row direction as a group, and the
groups of the first group pixels and the second group pixels
alternate in a column direction.
3. The image pickup device of claim 2, wherein: the plurality of
pixels further comprise third group pixels and fourth group pixels
that are each classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof; the confined light-receiving region of the third
group pixels is arranged biased further to the first direction
relative to the confined light-receiving region of the first group
pixels; the confined light-receiving region of the fourth group
pixels is arranged biased further to the second direction relative
to the confined light-receiving region of the second group pixels;
and the third group pixels and the fourth group pixels are each
consecutively arranged in the row direction as a group, and the
groups of the first group pixels, the second group pixels, the
third group pixels, and the fourth group pixels alternate in the
column direction.
4. The image pickup device of claim 1, wherein: the plurality of
pixels further comprise fifth group pixels and sixth group pixels
that are each classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof the confined light-receiving region of the first
group pixels is arranged biased to a first direction defined along
a row direction; the confined light-receiving region of the second
group pixels is arranged biased to a second direction opposite to
the first direction; the confined light-receiving region of the
fifth group pixels is arranged biased to a third direction defined
along a column direction perpendicular to the row direction; and
the confined light-receiving region of the sixth group pixels is
arranged biased to a fourth direction opposite to the third
direction.
5. The image pickup device of claim 4, wherein: the image pickup
device comprises: a plurality of first regions in which the first
group pixels and the second group pixels are arranged; and a
plurality of second regions in which the fifth group pixels and the
sixth group pixels are arranged; the first group pixels and the
second group pixels are each consecutively arranged in the row
direction in the first regions as a group, and the groups of the
first group pixels and the second group pixels alternate in the
column direction in the first regions; and the fifth group pixels
and the sixth group pixels are each consecutively arranged in the
column direction in the second regions as a group, and the groups
of the fifth group pixels and the sixth group pixels alternate in
the row direction in the second regions.
6. The image pickup device of claim 1, wherein: the confined
light-receiving region of the phase-difference detection sub-pixel
of the first group pixels is arranged in a center of the
corresponding phase-difference detection sub-pixel, or is arranged
biased to a first direction defined along a row direction; the
confined light-receiving region of the phase-difference detection
sub-pixel of the second group pixels is arranged in a center of the
corresponding phase-difference detection sub-pixel, or is arranged
biased to a second direction opposite to the first direction; the
confined light-receiving region of the phase-difference detection
sub-pixel of the first group pixels is arranged in a center of the
corresponding phase-difference detection sub-pixel if the
corresponding phase-difference detection sub-pixel is in a region
of the image pickup device biased to the first direction from an
optical axis, and is arranged biased to the first direction if the
corresponding phase-difference detection sub-pixel is in a region
of the image pickup device biased to the second direction from the
optical axis; and the confined light-receiving region of the
phase-difference detection sub-pixel of the second group pixels is
arranged in a center of the corresponding phase-difference
detection sub-pixel if the corresponding phase-difference detection
sub-pixel is in a region of the image pickup device biased to the
second direction from the optical axis, and is arranged biased to
the second direction if the corresponding phase-difference
detection sub-pixel is in a region of the image pickup device
biased to the first direction from the optical axis.
7. The image pickup device of claim 1, wherein: the plurality of
pixels further comprise fifth group pixels and sixth group pixels
that are each classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof; the confined light-receiving region of the
phase-difference detection sub-pixel of the first group pixels is
arranged in a center of the corresponding phase-difference
detection sub-pixel, or is arranged biased to a first direction
defined along a row direction; the confined light-receiving region
of the phase-difference detection sub-pixel of the second group
pixels is arranged in a center of the corresponding
phase-difference detection sub-pixel, or is arranged biased to a
second direction opposite to the first direction; the confined
light-receiving region of the phase-difference detection sub-pixel
of the fifth group pixels is arranged in a center of the
corresponding phase-difference detection sub-pixel, or is arranged
biased to a third direction defined along a column direction
perpendicular to the row direction; and the confined
light-receiving region of the phase-difference detection sub-pixel
of the sixth group pixels is arranged in a center of the
corresponding phase-difference detection sub-pixel, or is arranged
biased to a fourth direction opposite to the third direction.
8. The image pickup device of claim 7, wherein: the confined
light-receiving region of the phase-difference detection sub-pixel
of the first group pixels is arranged in a center of the
corresponding phase-difference detection sub-pixel if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the first direction from an optical axis,
and is arranged biased to the first direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the second direction from the optical axis;
the confined light-receiving region of the phase-difference
detection sub-pixel of the second group pixels is arranged in a
center of the corresponding phase-difference detection sub-pixel if
the phase-difference detection sub-pixel is in a region of the
image pickup device biased to the second direction from an optical
axis, and is arranged biased to the second direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the first direction from the optical axis;
the confined light-receiving region of the phase-difference
detection sub-pixel of the fifth group pixels is arranged in a
center of the corresponding phase-difference detection sub-pixel if
the phase-difference detection sub-pixel is in a region of the
image pickup device biased to the third direction from the optical
axis, and is arranged biased to the third direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the fourth direction from the optical axis;
and the confined light-receiving region of the phase-difference
detection sub-pixel of the sixth group pixels is arranged in a
center of the corresponding phase-difference detection sub-pixel if
the phase-difference detection sub-pixel is in a region of the
image pickup device biased to the fourth direction from the optical
axis, and is arranged biased to the fourth direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the third direction from the optical
axis.
9. The image pickup device of claim 1, wherein the plurality of
light-receiving sub-pixels are larger in size then the
phase-difference detection sub-pixel, and each light-receiving
sub-pixel has a light-receiving region in a center thereof.
10. The image pickup device of claim 9, wherein the plurality of
light-receiving sub-pixels and the phase-difference detection
sub-pixel each comprise: a photodiode layer for photoelectrically
converting incident light; a mask layer comprising a predetermined
aperture for defining the confined light-receiving regions and
formed on the photodiode layer; and a microlens for focusing
incident light and formed in the mask layer.
11. A digital photographing apparatus comprising: an optical system
for focusing light incident from a subject; an image pickup device
that photoelectrically converts the light incident through the
optical system and comprises a plurality of pixels; and a
phase-difference auto-focusing (AF) unit for determining whether a
current state is an in-focus state from a phase-difference
detection signal generated by the image pickup device; wherein the
image pickup device comprises a plurality of pixels arranged over
an entire region of the image pickup device, each pixel comprising:
a plurality of light-receiving sub-pixels that generate an image
pickup signal from incident light; and a phase-difference detection
sub-pixel having a confined light-receiving region and for
generating and outputting the phase-difference detection signal the
plurality of pixels comprises first group pixels and second group
pixels that each are classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof; and the confined light-receiving region of the
phase-difference detection sub-pixel of the first group pixels and
the confined light-receiving region of the phase-difference
detection sub-pixel in the second group pixels are arranged biased
to opposite directions.
12. The digital photographing apparatus of claim 11, wherein the
phase-difference AF processing unit determines whether the current
state is in the in-focus state by detecting magnitudes of the
phase-difference detection signals of the first group pixels and
the second group pixels according to pixel regions of the image
pickup device, and determines a direction in which to move a lens
to be in the in-focus state.
13. The digital photographing apparatus of claim 11, wherein: the
confined light-receiving region of the first group pixels is
arranged biased to a first direction defined along a row direction;
the confined light-receiving region of the second group pixels is
arranged biased to a second direction opposite to the first
direction; and the first group pixels and the second group pixels
are each consecutively arranged in the row direction as a group,
and the groups of the first group pixels and the second group
pixels alternate in a column direction; the phase-difference AF
processing unit determines that the current state is in the
in-focus state if, in a region of the image pickup device that is
on an optical axis, the phase-difference detection signal of the
first group pixels and the phase-difference detection signal of the
second group pixels are detected to be greater than or equal to a
critical level; and if either the phase-difference detection signal
of the first group pixels or the phase-difference detection signal
of the second group pixels is detected to be less than the critical
level, the phase-difference AF processing unit determines that the
current state is in a front focus state if, in a region of the
image pickup device biased to the first direction from the optical
axis, the phase-difference detection signal of the second group
pixels is detected to be greater than or equal to the critical
level; and the phase-difference detection signal of the first group
pixels is detected to be less than the critical level; and
determines that the current state is in a back focus state if, in
the region of the image pickup device biased to the first direction
from the optical axis, the phase-difference detection signal of the
first group pixels is detected to be greater than or equal to the
critical level, and the phase-difference detection signal of the
second group pixels is detected to be less than the critical
level.
14. The digital photographing apparatus of claim 11, wherein: the
plurality of pixels further comprise third group pixels and fourth
group pixels that each are classified according to an arrangement
of the confined light-receiving region of the phase-difference
detection sub-pixel thereof; the confined light-receiving region of
the third group pixels is arranged biased further to the first
direction relative to the confined light-receiving region of the
first group pixels; the confined light-receiving region of the
fourth group pixels is arranged biased further to the second
direction relative to the confined light-receiving region of the
second group pixels; the phase-difference AF processing unit
determines whether the current state is in the in-focus state using
the phase-difference detection signals of the first group pixels
and the second group pixels in a first focal distance region, and
using the phase-difference detection signals of the third group
pixels and the fourth group pixels in a second focal distance
region with a focal distance shorter than that in the first focal
distance region.
15. The digital photographing apparatus of claim 11, wherein: the
plurality of pixels further comprise fifth group pixels and sixth
group pixels that are each classified according to an arrangement
of the confined light-receiving region of the phase-difference
detection sub-pixel thereof; the confined light-receiving region of
the first group pixels is arranged biased to a first direction
defined along a row direction; the confined light-receiving region
of the second group pixels is arranged biased to a second direction
opposite to the first direction; the confined light-receiving
region of the fifth group pixels is arranged biased to a third
direction defined along a column direction perpendicular to the row
direction; the confined light-receiving region of the sixth group
pixels is arranged biased to a fourth direction opposite to the
third direction; wherein the phase-difference AF processing unit
determines that the current state is in the in-focus state if, in a
region of the image pickup device that is on an optical axis, the
phase-difference detection signals of the first, second, fifth and
sixth group pixels are detected to be greater than or equal to a
critical level; if the phase-difference detection signals of the
first, second, fifth and sixth group pixels are detected to be less
than the critical level, the phase-difference AF processing unit
determines that the current state is in a front focus state if, in
a region of the image pickup device biased to the first direction
from the optical axis, the phase-difference detection signal of the
second group pixels is detected to be greater than or equal to the
critical level, and the phase-difference detection signal of the
first group pixels is detected to be less than the critical level;
the phase-difference AF processing unit determines that the current
state is in the front focus state if in a region of the image
pickup device biased to the third direction from the optical axis
the phase-difference detection signal of the sixth group pixels is
detected to be greater than or equal to the critical level, and the
phase-difference detection signal of the fifth group pixels is
detected to be less than the critical level; the phase-difference
AF processing unit determines that the current state is in a back
focus state if, in the region of the image pickup device biased to
the first direction from the optical axis, the phase-difference
detection signal of the first group pixels is detected to be
greater than or equal to the critical level, and the
phase-difference detection signal of the second group pixels is
detected to be less than the critical level; and the
phase-difference AF processing unit determines that the current
state is in the back focus state if, in the region of the image
pickup device biased to the third direction from the optical axis,
the phase-difference detection signal of the fifth group pixels is
detected to be greater than or equal to the critical level, and the
phase-difference detection signal of the sixth group pixels is
detected to be less than the critical level.
16. The digital photographing apparatus of claim 11, further
comprising: an interpolation unit for performing interpolation on
the plurality of light-receiving sub-pixels and the
phase-difference detection sub-pixel; wherein the plurality of
light-receiving sub-pixels are of different colors, and the
interpolation unit performs interpolation on the light receiving
sub-pixels of the same color using neighboring pixels of the same
pattern over the entire region of the image pickup device, and
performs interpolation on the phase-difference detection sub-pixels
using neighboring pixels of the same pattern over the entire region
of the image pickup device.
17. The digital photographing apparatus of claim 11, further
comprising: a contrast AF processing unit for extracting contrast
information from an image pickup signal generated by a plurality of
the light-receiving sub-pixels and determining whether the current
state is in the in-focus state using the contrast information; and
a lens driving unit for driving a lens of the optical system
according to a result of the in-focus state determination by the
phase-difference AF processing unit and a result of the in-focus
state determination by the contrast AF processing unit.
18. An auto-focusing method of a digital photographing apparatus
including an image pickup device, the image pickup device
comprising a plurality of pixels arranged over an entire region of
the image pickup device, each pixel comprising: a plurality of
light-receiving sub-pixels that generate an image pickup signal
from incident light; and a phase-difference detection sub-pixel
having a confined light-receiving region and for generating and
outputting the phase-difference detection signal, wherein the
plurality of pixels comprises first group pixels and second group
pixels that are each classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof, and the confined light-receiving region of the
phase-difference detection sub-pixel of the first group pixels and
the confined light-receiving region of the phase-difference
detection sub-pixel in the second group pixels are arranged biased
to opposite directions, the auto-focusing method comprising:
determining whether the current state is in an in-focus state by
detecting magnitudes of the phase-difference detection signals of
the first group pixels and the second group pixels according to
pixel regions of the image pickup device; and determining whether
the current state is in a front focus state or in a back focus
state if the current state is not in the in-focus state.
19. The auto-focusing method of claim 18, wherein the confined
light-receiving region of the first group pixels is arranged biased
to a first direction defined along a row direction; the confined
light-receiving region of the second group pixels is arranged
biased to a second direction opposite to the first direction; and
the first group pixels and the second group pixels are each
consecutively arranged in the row direction as a group, and the
groups of the first group pixels and the second group pixels
alternate in a column direction, the auto-focusing method further
comprising: determining that the current state is in the in-focus
state if, in a region of the image pickup device that is on an
optical axis, the phase-difference detection signal of the first
group pixels and the phase-difference detection signal of the
second group pixels are detected to be greater than or equal to a
critical level; if, in the region of the image pickup device that
is on the optical axis, the phase-difference detection signal of
the first group pixels and the phase-difference detection signal of
the second group pixels are detected to be less than the critical
level, determining that the current state is in the front focus
state if, in a region of the image pickup device biased to the
first direction from the optical axis the phase-difference
detection signal of the second group pixels is detected to be
greater than or equal to the critical level, and the
phase-difference detection signal of the first group pixels is
detected to be less than the critical level; and determining that
the current state is in the back focus state if, in the region of
the image pickup device biased to the first direction from the
optical axis, the phase-difference detection signal of the first
group pixels is detected to be greater than or equal to the
critical level, and the phase-difference detection signal of the
second group pixels is detected to be less than the critical
level.
20. The auto-focusing method of claim 18, wherein the plurality of
pixels further comprise third group pixels and fourth group pixels
that are each classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof; the confined light-receiving region of the third
group pixels is arranged biased further to the first direction
relative to the confined light-receiving region of the first group
pixels; and the confined light-receiving region of the fourth group
pixels is arranged biased further to the second direction relative
to the confined light-receiving region of the second group pixels,
the auto-focusing method further comprising: determining whether
the current state is in the in-focus state using the
phase-difference detection signals of the first group pixels and
the second group pixels in a first focal distance region; and
determining whether the current state is in the in-focus state
using the phase-difference detection signals of the third group
pixels and the fourth group pixels in a second focal distance
region with a focal distance shorter than that in the first focal
distance region.
21. The auto-focusing method of claim 18, wherein: the plurality of
pixels further comprise fifth group pixels and sixth group pixels
that each are classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof; the confined light-receiving region of the first
group pixels is arranged biased to a first direction defined along
a row direction; the confined light-receiving region of the second
group pixels is arranged biased to a second direction opposite to
the first direction; the confined light-receiving region of the
fifth group pixels is arranged biased to a third direction defined
along a column direction perpendicular to the row direction; and
the confined light-receiving region of the sixth group pixels is
arranged biased to a fourth direction opposite to the third
direction, the auto-focusing method further comprising: determining
that the current state is in the in-focus state if, in a region of
the image pickup device that is on an optical axis, the
phase-difference detection signals of the first, second, fifth and
sixth group pixels are detected to be greater than or equal to a
critical level; and if, in the region of the image pickup device
that is on the optical axis, the phase-difference detection signals
of the first, second, fifth and sixth group pixels are detected to
be less than the critical level, determining that the current state
is in the front focus state if, in a region of the image pickup
device biased to the first direction from the optical axis, the
phase-difference detection signal of the second group pixels is
detected to be greater than or equal to the critical level, and the
phase-difference detection signal of the first group pixels is
detected to be less than the critical level, determining that the
current state is in the front focus state if, in a region of the
image pickup device biased to the third direction from the optical
axis, the phase-difference detection signal of the sixth group
pixels is detected to be greater than or equal to the critical
level, and the phase-difference detection signal of the fifth group
pixels is detected to be less than the critical level; determining
that the current state is in the back focus state if, in the region
of the image pickup device biased to the first direction from the
optical axis, the phase-difference detection signal of the first
group pixels is detected to be greater than or equal to the
critical level, and the phase-difference detection signal of the
second group pixels is detected to be less than the critical level;
and determining that the current state is in the back focus state
if, in the region of the image pickup device biased to the third
direction from the optical axis, the phase-difference detection
signal of the fifth group pixels is detected to be greater than or
equal to the critical level, and the phase-difference detection
signal of the sixth group pixels is detected to be less than the
critical level.
22. The auto-focusing method of claim 18, wherein the plurality of
light-receiving sub-pixels are of different colors, the
auto-focusing method comprising: performing interpolation on the
light receiving sub-pixels using neighboring pixels of the same
pattern over the entire region of the image pickup device; and
performing interpolation on the phase-difference detection
sub-pixels using neighboring pixels of the same pattern over the
entire region of the image pickup device.
23. The auto-focusing method of claim 18, further comprising:
extracting contrast information from the image pickup signal
generated by a plurality of the light-receiving sub-pixels and
determining whether the current state is in the in-focus state
using the contrast information; and driving a lens according to a
result of the in-focus state determination using the
phase-difference detection signals, and a result of the in-focus
state determination using the contrast information.
24. A computer readable storage medium storing computer program
codes for executing an auto-focusing method of a digital
photographing apparatus including an image pickup device, wherein
the image pickup device comprises a plurality of pixels arranged
over an entire region of the image pickup device, each pixel
comprising: a plurality of light-receiving sub-pixels that generate
an image pickup signal from incident light; and a phase-difference
detection sub-pixel having a confined light-receiving region and
for generating and outputting the phase-difference detection
signal; the plurality of pixels comprise first group pixels and
second group pixels that each are classified according to an
arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof, and the confined
light-receiving region of the phase-difference detection sub-pixel
of the first group pixels and the confined light-receiving region
of the phase-difference detection sub-pixel in the second group
pixels are arranged biased to opposite directions, the
auto-focusing method comprising: determining whether the current
state is in an in-focus state by detecting the magnitudes of the
phase-difference detection signals of the first group pixels and
the second group pixels according to pixel regions of the image
pickup device; and determining whether the current state is in a
front focus state or in a back focus state if not in an in-focus
state.
Description
[0001] CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0002] This application claims the benefit of Korean Patent
Application No. 10-2011-0045682, filed on May 16, 2011, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND
[0003] The present invention relates to an image pickup device, a
digital photographing device using the image pickup device, an
auto-focusing method, and a computer-readable storage medium for
performing the auto-focusing method.
[0004] Auto-focusing (AF) systems are widely used in photographing
apparatuses such as digital compact cameras, lens-changeable
cameras, camcorders, or the like. AF systems may be classified into
either phase difference AF systems using phase difference detection
or contrast AF systems using contrast detection.
[0005] A phase difference AF system includes a phase difference AF
sensor separate from an image pickup device, and performs AF using
a defocus amount of a lens calculated from an output of the phase
difference AF sensor. For phase difference AF, an additional mirror
for the phase difference AF is required. For example, to apply
phase difference AF to a digital single lens reflection (DSLR)
camera, a sub-mirror for guiding incident light onto the phase
difference AF sensor is further used along with a main mirror.
Phase difference AF ensures high-speed, high-performance AF, but is
costly due to an extra optical system needed for the phase
difference AF.
[0006] A contrast AF system extracts high-frequency data from image
data output from an image pickup device and controls AF to maximize
the high-frequency component. To this end, the contrast AF system
requires a signal processing circuit, but no extra sensor or
optical system, and thus may be established at relatively low
costs. However, the contrast AF system is low in speed and
precision relative to phase difference AF systems.
SUMMARY
[0007] Various embodiments of the present invention perform phase
difference auto-focusing (AF) without using either an extra phase
difference AF sensor or optical system. These perform uniform
interpolation over the entire pixel region of an image pickup
device including phase-difference detection sub-pixels, thereby
avoiding an image quality degradation even with the
phase-difference sub-pixels arranged in the image pickup device.
They also define a confined light-receiving region of
phase-difference detection sub-pixels that are biased to a
direction according to a pixel region of an image pickup device,
thereby improving auto-focusing performance on outer pixels.
[0008] According to an embodiment of the present invention, there
is provided an image pickup device including a plurality of pixels
arranged over an entire region of the image pickup device, each
pixel including: a plurality of light-receiving sub-pixels that
generate an image pickup signal from incident light; and a
phase-difference detection sub-pixel having a confined
light-receiving region, wherein the plurality of pixels may include
first group pixels and second group pixels that are each classified
according to an arrangement of the confined light-receiving region
of the phase-difference detection sub-pixel thereof, and the
confined light-receiving region of the phase-difference detection
sub-pixel of the first group pixels and the confined
light-receiving region of the phase-difference detection sub-pixel
in the second group pixels may be arranged biased to opposite
directions.
[0009] The confined light-receiving region of the first group
pixels may be arranged biased to a first direction defined along a
row direction, the confined light-receiving region of the second
group pixels may be arranged biased to a second direction opposite
to the first direction, and the first group pixels and the second
group pixels may be each consecutively arranged in the row
direction as a group, and the groups of the first group pixels and
the second group pixels may alternate in a column direction.
[0010] The plurality of pixels may further include third group
pixels and fourth group pixels that are each classified according
to an arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof, the confined
light-receiving region of the third group pixels may be arranged
biased further to the first direction relative to the confined
light-receiving region of the first group pixels, the confined
light-receiving region of the fourth group pixels may be arranged
biased further to the second direction relative to the confined
light-receiving region of the second group pixels, and the third
group pixels and the fourth group pixels may be each consecutively
arranged in the row direction as a group, and the groups of the
first group pixels, the second group pixels, the third group
pixels, and the fourth group pixels alternate in the column
direction.
[0011] The plurality of pixels may further include fifth group
pixels and sixth group pixels that are each classified according to
an arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof, the confined
light-receiving region of the first group pixels may be arranged
biased to a first direction defined along a row direction, the
confined light-receiving region of the second group pixels may be
arranged biased to a second direction opposite to the first
direction, the confined light-receiving region of the fifth group
pixels may be arranged biased to a third direction defined along a
column direction perpendicular to the row direction, and the
confined light-receiving region of the sixth group pixels may be
arranged biased to a fourth direction opposite to the third
direction. The image pickup device may include: a plurality of
first regions in which the first group pixels and the second group
pixels are arranged; and a plurality of second regions in which the
fifth group pixels and the sixth group pixels are arranged. The
first group pixels and the second group pixels may be each
consecutively arranged in the row direction in the first regions as
a group, and the groups of the first group pixels and the second
group pixels may alternate in the column direction in the first
regions. The fifth group pixels and the sixth group pixels may be
each consecutively arranged in the column direction in the second
regions as a group, and the groups of the fifth group pixels and
the sixth group pixels may alternate in the row direction in the
second regions.
[0012] The confined light-receiving region of the phase-difference
detection sub-pixel of the first group pixels may be arranged in a
center of the corresponding phase-difference detection sub-pixel,
or may be arranged biased to a first direction defined along a row
direction. The confined light-receiving region of the
phase-difference detection sub-pixel of the second group pixels may
be arranged in a center of the corresponding phase-difference
detection sub-pixel, or may be arranged biased to a second
direction opposite to the first direction. The confined
light-receiving region of the phase-difference detection sub-pixel
of the first group pixels may be arranged in a center of the
corresponding phase-difference detection sub-pixel if the
corresponding phase-difference detection sub-pixel is in a region
of the image pickup device biased to the first direction from an
optical axis, and may be arranged biased to the first direction if
the corresponding phase-difference detection sub-pixel is in a
region of the image pickup device biased to the second direction
from the optical axis. The confined light-receiving region of the
phase-difference detection sub-pixel of the second group pixels may
be arranged in a center of the corresponding phase-difference
detection sub-pixel if the corresponding phase-difference detection
sub-pixel is in a region of the image pickup device biased to the
second direction from the optical axis, and may be arranged biased
to the second direction if the corresponding phase-difference
detection sub-pixel is in a region of the image pickup device
biased to the first direction from the optical axis.
[0013] The plurality of pixels may further include fifth group
pixels and sixth group pixels that are each classified according to
an arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof. The confined
light-receiving region of the phase-difference detection sub-pixel
of the first group pixels may be arranged in a center of the
corresponding phase-difference detection sub-pixel, or may be
arranged biased to a first direction defined along a row direction.
The confined light-receiving region of the phase-difference
detection sub-pixel of the second group pixels may be arranged in a
center of the corresponding phase-difference detection sub-pixel,
or may be arranged biased to a second direction opposite to the
first direction. The confined light-receiving region of the
phase-difference detection sub-pixel of the fifth group pixels may
be arranged in a center of the corresponding phase-difference
detection sub-pixel, or may be arranged biased to a third direction
defined along a column direction perpendicular to the row
direction. The confined light-receiving region of the
phase-difference detection sub-pixel of the sixth group pixels may
be arranged in a center of the corresponding phase-difference
detection sub-pixel, or may be arranged biased to a fourth
direction opposite to the third direction.
[0014] The confined light-receiving region of the phase-difference
detection sub-pixel of the first group pixels may be arranged in a
center of the corresponding phase-difference detection sub-pixel if
the phase-difference detection sub-pixel is in a region of the
image pickup device biased to the first direction from an optical
axis, and may be arranged biased to the first direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the second direction from the optical axis.
The confined light-receiving region of the phase-difference
detection sub-pixel of the second group pixels may be arranged in a
center of the corresponding phase-difference detection sub-pixel if
the phase-difference detection sub-pixel is in a region of the
image pickup device biased to the second direction from an optical
axis, and may be arranged biased to the second direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the first direction from the optical axis.
The confined light-receiving region of the phase-difference
detection sub-pixel of the fifth group pixels may be arranged in a
center of the corresponding phase-difference detection sub-pixel if
the phase-difference detection sub-pixel is in a region of the
image pickup device biased to the third direction from the optical
axis, and may be arranged biased to the third direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the fourth direction from the optical axis.
The confined light-receiving region of the phase-difference
detection sub-pixel of the sixth group pixels may be arranged in a
center of the corresponding phase-difference detection sub-pixel if
the phase-difference detection sub-pixel is in a region of the
image pickup device biased to the fourth direction from the optical
axis, and may be arranged biased to the fourth direction if the
phase-difference detection sub-pixel is in a region of the image
pickup device biased to the third direction from the optical
axis.
[0015] The plurality of light-receiving sub-pixels may be larger in
size than the phase-difference detection sub-pixel, and each
light-receiving sub-pixel may have a light-receiving region in a
center thereof.
[0016] The plurality of light-receiving sub-pixels and the
phase-difference detection sub-pixel may each include: a photodiode
layer for photoelectrically converting incident light; a mask layer
including a predetermined aperture for defining the confined
light-receiving regions and formed on the photodiode layer; and a
microlens for focusing incident light and formed in the mask
layer.
[0017] According to another aspect, there is provided a digital
photographing apparatus including: an optical system for focusing
light incident from a subject; an image pickup device that
photoelectrically converts the light incident through the optical
system and includes a plurality of pixels; and a phase-difference
auto-focusing (AF) unit for determining whether a current state is
an in-focus state from a phase-difference detection signal
generated by the image pickup device, wherein the image pickup
device may include a plurality of pixels arranged over an entire
region of the image pickup device, each pixel including: a
plurality of light-receiving sub-pixels that generate an image
pickup signal from incident light; and a phase-difference detection
sub-pixel having a confined light-receiving region and for
generating and outputting the phase-difference detection signal.
The plurality of pixels may include first group pixels and second
group pixels that each are classified according to an arrangement
of the confined light-receiving region of the phase-difference
detection sub-pixel thereof, and the confined light-receiving
region of the phase-difference detection sub-pixel of the first
group pixels and the confined light-receiving region of the
phase-difference detection sub-pixel in the second group pixels may
be arranged biased to opposite directions.
[0018] The phase-difference AF processing unit may determine
whether the current state is in the in-focus state by detecting
magnitudes of the phase-difference detection signals of the first
group pixels and the second group pixels according to pixel regions
of the image pickup device, and may determine a direction in which
to move a lens to be in the in-focus state.
[0019] The confined light-receiving region of the first group
pixels may be arranged biased to a first direction defined along a
row direction, the confined light-receiving region of the second
group pixels may be arranged biased to a second direction opposite
to the first direction, and the first group pixels and the second
group pixels may each be consecutively arranged in the row
direction as a group, and the groups of the first group pixels and
the second group pixels alternate in a column direction. The
phase-difference AF processing unit may determine that the current
state is in the in-focus state if, in a region of the image pickup
device that is on an optical axis, the phase-difference detection
signal of the first group pixels and the phase-difference detection
signal of the second group pixels are detected to be greater than
or equal to a critical level. If either the phase-difference
detection signal of the first group pixels or the phase-difference
detection signal of the second group pixels is detected to be less
than the critical level, the phase-difference AF processing unit
may determine that the current state is in a front focus state if,
in a region of the image pickup device biased to the first
direction from the optical axis, the phase-difference detection
signal of the second group pixels is detected to be greater than or
equal to the critical level, and the phase-difference detection
signal of the first group pixels may be detected to be less than
the critical level; and determines that the current state is in a
back focus state if, in the region of the image pickup device
biased to the first direction from the optical axis, the
phase-difference detection signal of the first group pixels is
detected to be greater than or equal to the critical level, and the
phase-difference detection signal of the second group pixels is
detected to be less than the critical level.
[0020] The plurality of pixels may further include third group
pixels and fourth group pixels that each are classified according
to an arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof, the confined
light-receiving region of the third group pixels may be arranged
biased further to the first direction relative to the confined
light-receiving region of the first group pixels, and the confined
light-receiving region of the fourth group pixels may be arranged
biased further to the second direction relative to the confined
light-receiving region of the second group pixels, wherein the
phase-difference AF processing unit may determine whether the
current state is in the in-focus state using the phase-difference
detection signals of the first group pixels and the second group
pixels in a first focal distance region, and using the
phase-difference detection signals of the third group pixels and
the fourth group pixels in a second focal distance region with a
focal distance shorter than that in the first focal distance
region.
[0021] The plurality of pixels may further include fifth group
pixels and sixth group pixels that are each classified according to
an arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof, the confined
light-receiving region of the first group pixels may be arranged
biased to a first direction defined along a row direction, the
confined light-receiving region of the second group pixels may be
arranged biased to a second direction opposite to the first
direction, the confined light-receiving region of the fifth group
pixels may be arranged biased to a third direction defined along a
column direction perpendicular to the row direction, and the
confined light-receiving region of the sixth group pixels may be
arranged biased to a fourth direction opposite to the third
direction. The phase-difference AF processing unit may determine
that the current state is in the in-focus state if, in a region of
the image pickup device that is on an optical axis, the
phase-difference detection signals of the first, second, fifth and
sixth group pixels are detected to be greater than or equal to a
critical level. If the phase-difference detection signals of the
first, second, fifth and sixth group pixels are detected to be less
than the critical level, the phase-difference AF processing unit
may determine that the current state is in a front focus state if,
in a region of the image pickup device biased to the first
direction from the optical axis, the phase-difference detection
signal of the second group pixels is detected to be greater than or
equal to the critical level, and the phase-difference detection
signal of the first group pixels is detected to be less than the
critical level; the phase-difference AF processing unit may
determine that the current state is in the front focus state if, in
a region of the image pickup device biased to the third direction
from the optical axis, the phase-difference detection signal of the
sixth group pixels is detected to be greater than or equal to the
critical level, and the phase-difference detection signal of the
fifth group pixels is detected to be less than the critical level;
the phase-difference AF processing unit may determine that the
current state is in a back focus state if, in the region of the
image pickup device biased to the first direction from the optical
axis, the phase-difference detection signal of the first group
pixels is detected to be greater than or equal to the critical
level, and the phase-difference detection signal of the second
group pixels is detected to be less than the critical level; and
the phase-difference AF processing unit may determine that the
current state is in the back focus state if, in the region of the
image pickup device biased to the third direction from the optical
axis, the phase-difference detection signal of the fifth group
pixels is detected to be greater than or equal to the critical
level, and the phase-difference detection signal of the sixth group
pixels is detected to be less than the critical level.
[0022] The digital photographing apparatus may further include an
interpolation unit for performing interpolation on the plurality of
light-receiving sub-pixels and the phase-difference detection
sub-pixel, wherein the plurality of light-receiving sub-pixels may
be of different colors, and the interpolation unit may perform
interpolation on the light receiving sub-pixels of the same color
using neighboring pixels of the same pattern over the entire region
of the image pickup device, and may perform interpolation on the
phase-difference detection sub-pixels using neighboring pixels of
the same pattern over the entire region of the image pickup
device.
[0023] The digital photographing apparatus may further include: a
contrast AF processing unit for extracting contrast information
from an image pickup signal generated by a plurality of the
light-receiving sub-pixels and determining whether the current
state is in the in-focus state using the contrast information; and
a lens driving unit for driving a lens of the optical system
according to a result of the in-focus state determination by the
phase-difference AF processing unit and a result of the in-focus
state determination by the contrast AF processing unit.
[0024] According to another aspect, there is provided an
auto-focusing method of a digital photographing apparatus including
an image pickup device, the image pickup device including a
plurality of pixels arranged over an entire region of the image
pickup device, each pixel including: a plurality of light-receiving
sub-pixels that generate an image pickup signal from incident
light; and a phase-difference detection sub-pixel having a confined
light-receiving region and for generating and outputting the
phase-difference detection signal, wherein the plurality of pixels
may include first group pixels and second group pixels that are
each classified according to an arrangement of the confined
light-receiving region of the phase-difference detection sub-pixel
thereof, and the confined light-receiving region of the
phase-difference detection sub-pixel of the first group pixels and
the confined light-receiving region of the phase-difference
detection sub-pixel in the second group pixels may be arranged
biased to opposite directions, the auto-focusing method including:
determining whether the current state is in an in-focus state by
detecting magnitudes of the phase-difference detection signals of
the first group pixels and the second group pixels according to
pixel regions of the image pickup device; and determining whether
the current state is in a front focus state or in a back focus
state if the current state is not in the in-focus state.
[0025] The confined light-receiving region of the first group
pixels may be arranged biased to a first direction defined along a
row direction; the confined light-receiving region of the second
group pixels may be arranged biased to a second direction opposite
to the first direction; and the first group pixels and the second
group pixels may be each consecutively arranged in the row
direction as a group, and the groups of the first group pixels and
the second group pixels may alternate in a column direction, the
auto-focusing method further including: determining that the
current state is in the in-focus state if, in a region of the image
pickup device that is on an optical axis, the phase-difference
detection signal of the first group pixels and the phase-difference
detection signal of the second group pixels are detected to be
greater than or equal to a critical level; and if, in the region of
the image pickup device that is on the optical axis, the
phase-difference detection signal of the first group pixels and the
phase-difference detection signal of the second group pixels are
detected to be less than the critical level, determining that the
current state is in the front focus state if, in a region of the
image pickup device biased to the first direction from the optical
axis, the phase-difference detection signal of the second group
pixels is detected to be greater than or equal to the critical
level, and the phase-difference detection signal of the first group
pixels is detected to be less than the critical level, and
determining that the current state is in the back focus state if,
in the region of the image pickup device biased to the first
direction from the optical axis, the phase-difference detection
signal of the first group pixels is detected to be greater than or
equal to the critical level, and the phase-difference detection
signal of the second group pixels is detected to be less than the
critical level.
[0026] The plurality of pixels may further include third group
pixels and fourth group pixels that are each classified according
to an arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof; the confined
light-receiving region of the third group pixels may be arranged
biased further to the first direction relative to the confined
light-receiving region of the first group pixels; and the confined
light-receiving region of the fourth group pixels may be arranged
biased further to the second direction relative to the confined
light-receiving region of the second group pixels, the
auto-focusing method further including: determining whether the
current state is in the in-focus state using the phase-difference
detection signals of the first group pixels and the second group
pixels in a first focal distance region; and determining whether
the current state is in the in-focus state using the
phase-difference detection signals of the third group pixels and
the fourth group pixels in a second focal distance region with a
focal distance shorter than that in the first focal distance
region.
[0027] The plurality of pixels may further include fifth group
pixels and sixth group pixels that each are classified according to
an arrangement of the confined light-receiving region of the
phase-difference detection sub-pixel thereof; the confined
light-receiving region of the first group pixels may be arranged
biased to a first direction defined along a row direction; the
confined light-receiving region of the second group pixels may be
arranged biased to a second direction opposite to the first
direction; the confined light-receiving region of the fifth group
pixels may be arranged biased to a third direction defined along a
column direction perpendicular to the row direction; and the
confined light-receiving region of the sixth group pixels may be
arranged biased to a fourth direction opposite to the third
direction, the auto-focusing method further including: determining
that the current state is in the in-focus state if, in a region of
the image pickup device that is on an optical axis, the
phase-difference detection signals of the first, second, fifth and
sixth group pixels are detected to be greater than or equal to a
critical level; and if, in the region of the image pickup device
that is on the optical axis, the phase-difference detection signals
of the first, second, fifth and sixth group pixels are detected to
be less than the critical level, determining that the current state
is in the front focus state if, in a region of the image pickup
device biased to the first direction from the optical axis, the
phase-difference detection signal of the second group pixels is
detected to be greater than or equal to the critical level, and the
phase-difference detection signal of the first group pixels is
detected to be less than the critical level, determining that the
current state is in the front focus state if, in a region of the
image pickup device biased to the third direction from the optical
axis, the phase-difference detection signal of the sixth group
pixels is detected to be greater than or equal to the critical
level, and the phase-difference detection signal of the fifth group
pixels is detected to be less than the critical level, determining
that the current state is in the back focus state if, in the region
of the image pickup device biased to the first direction from the
optical axis, the phase-difference detection signal of the first
group pixels is detected to be greater than or equal to the
critical level, and the phase-difference detection signal of the
second group pixels is detected to be less than the critical level,
and determining that the current state is in the back focus state
if, in the region of the image pickup device biased to the third
direction from the optical axis, the phase-difference detection
signal of the fifth group pixels is detected to be greater than or
equal to the critical level, and the phase-difference detection
signal of the sixth group pixels is detected to be less than the
critical level.
[0028] The plurality of light-receiving sub-pixels may be of
different colors, the auto-focusing method including: performing
interpolation on the light receiving sub-pixels using neighboring
pixels of the same pattern over the entire region of the image
pickup device; and performing interpolation on the phase-difference
detection sub-pixels using neighboring pixels of the same pattern
over the entire region of the image pickup device.
[0029] The auto-focusing method may further include: extracting
contrast information from the image pickup signal generated by a
plurality of the light-receiving sub-pixels and determining whether
the current state is in the in-focus state using the contrast
information; and driving a lens according to a result of the
in-focus state determination using the phase-difference detection
signals, and a result of the in-focus state determination using the
contrast information.
[0030] According to another aspect, there is provided a computer
readable storage medium that stores computer program codes for
executing an auto-focusing method of a digital photographing
apparatus including an image pickup device, wherein the image
pickup device includes a plurality of pixels arranged over an
entire region of the image pickup device, each pixel including: a
plurality of light-receiving sub-pixels that generate an image
pickup signal from incident light; and a phase-difference detection
sub-pixel having a confined light-receiving region and for
generating and outputting the phase-difference detection signal;
the plurality of pixels include first group pixels and second group
pixels that each are classified according to an arrangement of the
confined light-receiving region of the phase-difference detection
sub-pixel thereof, and the confined light-receiving region of the
phase-difference detection sub-pixel of the first group pixels and
the confined light-receiving region of the phase-difference
detection sub-pixel in the second group pixels are arranged biased
to opposite directions, the auto-focusing method including:
determining whether the current state is in an in-focus state by
detecting the magnitudes of the phase-difference detection signals
of the first group pixels and the second group pixels according to
pixel regions of the image pickup device; and determining whether
the current state is in a front focus state or in a back focus
state if not in an in-focus state.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0032] FIG. 1 is a block diagram of a digital photographing
apparatus according to an exemplary embodiment of the present
invention;
[0033] FIGS. 2A-C are side view illustrations of structures of
phase difference detection sub-pixels and light receiving
sub-pixels included in an image pickup device according to an
embodiment of the present invention;
[0034] FIG. 3 is a perspective view illustrating a shooting pupil
of the image pickup device of FIG. 2, according to an embodiment of
the present invention;
[0035] FIG. 4 is a pictorial illustration showing arrangements of a
plurality of sub-pixels in a plurality of pixels, according to
embodiments of the present invention;
[0036] FIG. 5A is a pictorial illustration showing an arrangement
of a plurality of pixels according to an embodiment of the present
invention;
[0037] FIG. 5B is a pictorial illustration showing light-receiving
regions of phase-difference detection sub-pixels;
[0038] FIG. 5C is a pictorial illustration showing shooting
pupils;
[0039] FIG. 6 is a block diagram illustrating a configuration of a
CPU/DSP, and some elements of a photographing apparatus, according
to an embodiment of the present invention;
[0040] FIGS. 7A to 7C are pictorial diagrams and graphs for
describing a method of phase-difference auto-focusing (AF) in a
phase-difference AF processing unit;
[0041] FIGS. 8A-8D are pictorial diagrams for explaining
interpolation according to embodiments of the present
invention;
[0042] FIG. 9 is a block diagram illustrating a configuration of a
phase-difference AF processing unit according to an embodiment of
the present invention;
[0043] FIG. 10 is a flowchart illustrating an AF method according
to an embodiment of the present invention;
[0044] FIG. 11A is a pictorial diagram illustrating an arrangement
of a plurality of pixels according to another embodiment of the
present invention;
[0045] FIG. 11B is a pictorial diagram illustrating light-receiving
regions of phase-difference detection sub-pixels;
[0046] FIG. 11C is a pictorial diagram illustrating shooting
pupils; and
[0047] FIG. 11D is a side-view diagram for describing
phase-difference AF operations according to focal distances;
[0048] FIG. 12A is a pictorial diagram illustrating an arrangement
of a plurality of pixels according to another embodiment of the
present invention;
[0049] FIG. 12B is a pictorial diagram illustrating light-receiving
regions of phase-difference detection sub-pixels;
[0050] FIG. 12C is a pictorial diagram illustrating shooting
pupils; and
[0051] FIG. 13A is a pictorial diagram illustrating an arrangement
of a plurality of pixels according to another embodiment of the
present invention;
[0052] FIG. 13B is a pictorial diagram illustrating light-receiving
regions of phase-difference detection sub-pixels; and
[0053] FIG. 13C is a side view diagram for describing arrangements
of the phase-difference detection sub-pixels according to regions
of the image pickup device 118.
DETAILED DESCRIPTION
[0054] Certain embodiments are described more fully with reference
to the accompanying drawings, in which various inventive aspects
and features are shown. In the following description, various
features are described, and a detailed description of certain other
features that are obvious to one of ordinary skill in the art are
not provided to avoid obscuring the inventive subject matter. The
specification and drawings are provided for illustrative purposes
only and are not intended to limit the scope of the invention.
Unless otherwise defined, terms used herein have the meaning as
commonly understood by one of ordinary skill in the art to which
this invention belongs. It will be further understood that terms
should be interpreted as having a meaning that is consistent with
their meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0055] FIG. 1 is a block diagram of a digital photographing
apparatus 100 according to an exemplary embodiment of the present
invention.
[0056] According to the current embodiment, referring to FIG. 1,
the digital photographing apparatus 100 includes a photographing
unit 110, an analog signal processor 120, a memory 130, a
storage/read controller 140, a data storage unit 142, a program
storage unit 150, a display driving unit 162, a display unit 164, a
central processing unit/digital signal processor (CPU/DSP) 170, and
a manipulating unit 180.
[0057] The overall operation of the digital photographing apparatus
100 is controlled by the CPU/DSP 170. The CPU/DSP 170 provides a
control signal for operating individual elements, such as a lens
driving unit 112, an aperture driving unit 115, an image pickup
device control unit 119, and the like.
[0058] The photographing unit 110, which is an element for
generating an electric image signal from incident light, includes a
lens 111, the lens driving unit 112, an aperture 113, the aperture
driving unit 115, an image pickup device 118, and the image pickup
device control unit 119.
[0059] The lens 111 may include a plurality of lenses. The position
of the lens 111 is controlled by the lens driving unit 112. The
lens driving unit 112 may control the position of the lens 111
according to a control signal from the CPU/DSP 170.
[0060] The aperture 113, whose degree of opening may be controlled
by the aperture driving unit 115, may adjust an amount of light
incident onto the image pickup device 118.
[0061] An optical signal having passed the lens 111 and the
aperture 113 forms an image of a subject upon reaching a light
receiving surface of the image pickup device 118. The image pickup
device 118 may be a complementary metal oxide semiconductor image
sensor (CIS) for converting an optical signal to an electric
signal. A sensitivity of the image pickup device 118 may be
controlled by the image pickup device control unit 119. The image
pickup device control unit 119 may control the image pickup device
118 in real time according to a control signal automatically
generated in response to an input image signal, or a control signal
manually input by a user.
[0062] An exposure time (not shown) of the image pickup device 118
is controlled using a shutter (not shown). The shutter may be a
mechanical shutter for adjusting light incidence by moving the
aperture 113 or may be an electronic shutter for adjusting exposure
by supplying an electric signal to the image pickup device 118.
[0063] The analog signal processor 120 may perform noise reduction
processing, gain adjustment, waveform shaping, analog-to-digital
conversion, or the like on an analog signal from the image pickup
device 118.
[0064] A signal processed by the analog signal processor 120 may be
input to the CPU/DSP 170 directly or via the memory 130. The memory
130 may serve as a main memory of the digital photographing device
100, and temporarily store information required during an operation
of the CPU/DSP 170. The program storage unit 150 may store a
program for operating the digital photographing apparatus 100, such
as an operating system, an application system, and the like.
[0065] The digital photographing apparatus 100 may include the
display unit 164 for displaying an operation status or image
information captured by the digital photographing device 100. The
display unit 164 may provide visual information and/or auditory
information to the user. To provide visual information, the display
unit 164 may include, for example, a liquid crystal display (LCD)
panel, an organic light-emitting display (OLED) panel, or the like.
The display unit 164 may be a touch screen able to sense an input
when the screen is touched.
[0066] The display driving unit 162 may provide a driving signal to
the display unit 164.
[0067] The CPU/DSP 170 may process an input image pickup signal,
and may control each element of the digital photographing apparatus
100 according to the input image pickup signal or an external input
signal. The CPU/DSP 170 may reduce noise of the input image pickup
signal, and may perform image signal processing for image quality
improvement, for example, gamma correction, color filter array
interpolation, color matrix, color correction, and color
enhancement. Compression may be performed on image data generated
from the image signal processing for image quality improvement to
generate an image file, from which the image data may also be
restored. A compression format of the image data may be reversible
or irreversible. Appropriate examples of the compression format for
still images are a Joint Photographing Experts Group (JPEG) format,
a JPEG 2000 format, and the like. For moving pictures, a plurality
of frames may be compressed according to a Moving Picture Experts
Group (MPEG) standard, to generate a moving picture file. The image
file may be created according to an Exchangeable image file format
(Exif) standard.
[0068] Image data output from the CPU/DSP 170 may be input to the
storage/read controller 140 directly or via the memory 130. The
storage/read controller 140 may store the image data in the data
storage unit 142 automatically or according to a signal input from
the user. The storage/read controller 140 may read data of an image
from the image file stored in the data storage unit 142, and may
provide the data to the display driving unit 162 via the memory 130
or another path to display the image on the display unit 164. The
data storage unit 142 may be a separable component or a built-in
component of the digital photographing apparatus 100.
[0069] The CPU/DSP 170 may also perform obscurity coloring,
blurring, edge enhancing, image analysis processing, image
recognition, image effect processing, and the like. The image
recognition may be a face recognition process, a scene recognition
process, or the like. The CPU/DSP 170 may perform a display image
signal process for displaying on the display unit 164. For example,
bright level adjustment, color correction, contrast adjustment,
contour enhancing, screen dividing, creation, and synthesis of
images, such as a character image, may be performed. The CPU/DSP
170 may perform a predetermined image signal process on image data
to be displayed on an external monitor connected thereto, and
transfer the processed image data to display a corresponding image
on the external monitor.
[0070] The CPU/DSP 170 may execute a program stored in the memory
130, which is a program storage unit. The CPU/DSP 170 may include
an extra module for generating a control signal for auto-focusing,
zoom ratio changes, focus shifting, auto-exposure correction, and
the like, to provide the control signal to the aperture driving
unit 115, the lens driving unit 112, and the image pickup device
control unit 119, and may control constituent elements of the
digital photographing apparatus 100, such as the shutter, a flash,
and the like.
[0071] The manipulation unit 180 is an element via which the user
may input a control signal. The manipulation unit 180 may include a
variety of functional buttons, for example, a shutter-release
button for inputting a shutter-release signal for exposing the
image pickup device 118 to light for a predetermined time to
capture an image, a power button for inputting a control signal for
controlling powering on or off, a zoom button for widening or
narrowing an angle of view according to an input, a mode selection
button, and other buttons for photographing set value adjustment.
The manipulation unit 180 may be embodied in any form allowing a
user to input a control signal, for example, as a button, a
keyboard, a touch pad, a touch screen, a remote controller, or the
like.
[0072] FIGS. 2A-2C illustrate structures of phase difference
detection sub-pixels and light receiving sub-pixels included in the
image pickup device 118, according to an embodiment of the present
invention.
[0073] In the current embodiment of the present invention, the
image pickup device 118 may include a plurality of pixels each
including a plurality of sub-pixels. The plurality of sub-pixels
constituting each pixel may include at least one phase-difference
detection sub-pixel and a plurality of light-receiving
sub-pixels.
[0074] Each sub-pixel includes a photodiode layer 210, a mask layer
220, and a microlens 230.
[0075] The photodiode layer 210 converts an optical signal L into
an electric signal by photoelectric conversion. The intensity of
the electric signal may vary according to the intensity of the
optical signal L.
[0076] The mask layer 220 may define a light-receiving region of
each sub-pixel. To this end, the mask layer 220 may include an
aperture 212, 214 or 216 that corresponds to the light-receiving
region of each sub-pixel. The mask layer 220 may be implemented as
a metal mask.
[0077] The microlens 230 may focus the incident optical signal L
and transfer the same to the photodiode layer 210.
[0078] The phase difference detection sub-pixel (S) may have a
confined light-receiving region 212 and 214, which is biased to a
direction. The phase-difference detection sub-pixel S may include a
confined light-receiving region 212 and 214 that is biased to a
direction opposite to that of an adjacent pixel. The plurality of
pixels may be grouped according to arrangements of the confined
light-receiving regions 212 and 214 of the phase-difference
detection sub-pixels S.
[0079] According to the current embodiment of the present
invention, as illustrated in FIGS. 2A and 2B, the plurality of
pixels may include two kinds of phase-difference detection
sub-pixels sl and sr. A pixel including a first phase-difference
detection sub-pixel sl is referred to as a first group pixel, and a
pixel including a second phase-difference detection sub-pixel sr is
referred to as a second group pixel. A plurality of first
phase-difference detection sub-pixels sl may each have a confined
light-receiving region 212 biased to a first direction and the
first phase-difference detection sub-pixels sl may be arranged in a
row direction. A plurality of the second phase-difference detection
sub-pixels sr may each have a confined light-receiving region 214
biased to a second direction opposite to the first direction and
the second phase-difference detection sub-pixels sr may be arranged
in the row direction. The confined light-receiving regions 212 and
214 may form a shape extending along a column direction
perpendicular to the row direction.
[0080] The plurality of light-receiving sub-pixels may include a
combination of sub-pixels selected from, but not limited to, the
group consisting of red sub-pixels, blue sub-pixels, green
sub-pixels, and cyan sub-pixels. Each light-receiving sub-pixel is
formed over the entire region of the corresponding sub-pixel with a
light receiving region 216 disposed in a center of the
light-receiving sub-pixel. The light-receiving region 216 of each
light-receiving sub-pixel defines a sub-pixel and is surrounded by
the mask layer 220 to avoid interference with adjacent
sub-pixels.
[0081] FIG. 3 illustrates a shooting pupil of the image pickup
device 118, according to an embodiment of the present
invention.
[0082] According to the current embodiment of the present
invention, the image pickup device 118 may include a combination of
shooting pupils including a shooting pupil of a light-receiving
sub-pixel defined in circular or oval form with a center point on
an optical axis, a shooting pupil of a first phase-difference
detection sub-pixel sl defined in circular or oval form, biased to
a first direction with respect to the optical axis, and a shooting
pupil of a second phase-difference detection sub-pixel sr defined
in circular or oval form, biased to a second direction from the
optical axis. According to the current embodiment of the present
invention, a combination of these shooting pupils enables the image
pickup device 118 to generate an image pickup signal according to
incident light and at the same time to detect a phase difference
for auto-focusing (A F).
[0083] FIGS. 4A-F illustrate arrangements of a plurality of
sub-pixels in a plurality of pixels, according to embodiments of
the present invention.
[0084] The plurality of pixels may have the same sub-pixel pattern
over the entire region of the image pickup device 118. The
plurality of sub-pixels may have various patterns as illustrated in
FIGS. 4A-F. Referring to FIGS. 4A-F, R, G, and B denote red, green,
and blue light-receiving sub-pixels, respectively, and S denotes a
phase-difference detection sub-pixel. As illustrated in FIGS. 4A-F,
the phase-difference detection sub-pixel S, and the light-receiving
sub-pixels R, G, and B may be arranged in different manners.
Although the description of the present application focuses on the
embodiment where the plurality of pixels have the sub-pixel pattern
of FIG. 4A, for convenience of explanation, the plurality of pixels
may have various sub-pixel patterns.
[0085] FIG. 5A illustrates an arrangement of a plurality of pixels
according to an embodiment of the present invention. FIG. 5B
illustrates light-receiving regions of phase-difference detection
sub-pixels sl and sr. FIG. 5C illustrates shooting pupils.
[0086] In the current embodiment of the present invention, a
plurality of pixels are arranged in the image pickup device 118, as
illustrated in FIG. 5A, including phase-difference detection
sub-pixels sr and sl and pluralities of light-receiving sub-pixels
R, G, and B. Pixels including first phase-difference detection
sub-pixels sl are referred to as first group pixels G1, and pixels
including second phase-difference detection sub-pixels sr are
referred to as second group pixels G2.
[0087] As illustrated in FIG. 5B, a first phase-difference
detection sub-pixel sl may include a confined light-receiving
region 212 arranged biased to a first direction. A second
phase-difference detection sub-pixel sr may include a confined
light-receiving region 214 arranged biased to a second direction.
The confined light-receiving regions 212 and 214 of the first and
second phase-difference detection sub-pixels sl and sr may form a
shape extending along a column direction. As illustrated in FIG.
5A, pluralities of the first group pixels G1 and the second group
pixels G2 may each be consecutively arranged in a row direction as
a group, and the groups of the first group pixels G1 and the second
group pixels G2 may alternate in the column direction.
[0088] According to an embodiment of the present invention, the
confined light-receiving regions 212 and 214 may form shooting
pupils, as illustrated in FIG. 5C, in the image pickup device 118.
According to an embodiment of the present invention, an image
pickup signal may be generated from an optical signal incident
through a shooting pupil of a light-receiving sub-pixel, and
phase-difference AF may be performed using optical signals incident
through the shooting pupils of the first and second
phase-difference detection sub-pixels sl and sr.
[0089] FIG. 6 is a block diagram illustrating a configuration of a
CPU/DSP 170a, and some elements of the photographing apparatus 100,
according to an embodiment of the present invention.
[0090] Referring to FIG. 6, the CPU/DSP 170a may include an AF
signal extraction unit 610, an image pickup signal processing unit
620, a phase-difference AF processing unit 630, a contrast AF
processing unit 640, an AF microcomputer 650, an interpolation unit
660, and a codec 670. The image pickup device 118 may have a pixel
arrangement as illustrated in FIG. 5A.
[0091] The AF signal extraction unit 610 may extract
phase-difference detection signals from phase-difference detection
sub-pixels sl and sr of the image pickup device 118. The AF signal
extraction unit 610 may extract a first phase-difference detection
signal from a first phase-difference detection sub-pixel sl and a
second phase-difference detection signal from a second
phase-difference detection sub-pixel sr from each of the pixels.
The intensity of the first phase-difference signal and the second
phase-difference signal may be detected according to the location
of a pixel in row direction. In an embodiment of the present
invention, if a signal to noise ratio of the first phase-difference
detection signal or the second phase-difference detection signal of
pixels is low, the first phase-difference detection signals of
first phase-difference detection sub-pixels sl or the second
phase-difference detection signals of second phase-difference
detection sub-pixels sr may be integrated over rows.
[0092] The image pickup signal processing unit 620 may extract an
image pickup signal output from light-receiving sub-pixels R, G,
and B of the image pickup device 118, and process the image pickup
signal. The image pickup signal processing unit 620 may receive the
image pickup signal output from the image pickup device 118 and
processed in the analog signal processing unit 120 by, for example,
noise elimination, signal amplitude adjustment, analog-to-digital
conversion, and the like, to process the image pickup signal by,
for example, interpolation, white balancing, gamma processing, edge
enhancing, noise elimination, and the like. The image pickup signal
processing unit 620 may perform color coordinate conversion on an
RGB signal output from the image pickup device 630. For example,
the image pickup signal processing unit 620 may convert an RGB
signal to a YCC signal. The image pickup signal processing unit 620
may include the interpolation unit 660 for an interpolation
process.
[0093] The phase-difference AF processing unit 630 may perform
phase-difference AF on the first and second phase-difference
detection signals.
[0094] FIGS. 7A-1 to 7C-3 are diagrams for describing a method of
phase-difference AF in the phase-difference AF processing unit 630.
FIGS. 7A-1-7A-3 illustrate an in-focus state, FIGS. 7B-1-7B-3
illustrate a front focus state, and FIG. 7C-1-7C-3 illustrate a
back focus state. In FIGS. 7A-1 to 7C-3, a pixel location is
defined along a row direction.
[0095] In the in-focus state, as illustrated in FIG. 7A-1, an
optical signal incident onto the image pickup device 118 through
the lens 111 is focused on a center region of a light-receiving
surface of the image pickup device 118. In the in-focus state, as
illustrated in FIG. 7A-2, first phase-difference detection
sub-pixels sl and second phase-difference detection sub-pixels sr
in the center region of the light receiving surface may both
receive light, and a valid phase-difference detection signal may be
detected in the center region. Thus, if the magnitudes of the first
and second phase-difference detection signals in the center region
of the image pickup device 118 are detected as being greater than
or equal to a predetermined critical level, the phase-difference AF
processing unit 630 may determine that a current state is the
in-focus state.
[0096] In the front focus state, as illustrated in FIG. 7B-1, an
optical signal incident onto the image pickup device 118 through
the lens 111 is not focused on the center region of the
light-receiving surface of the image pickup device 118, and is
instead focused in front of the light-receiving surface of the
image pickup device 118.
[0097] In the front focus state, as illustrated in FIG. 7B-2, an
optical signal to be incident onto a first direction region AL of
the image pickup device 118, which is located off an optical axis
toward a first direction, may be blocked by a mask layer of a first
phase-difference detection sub-pixel sl, thus being unable to reach
a photodiode in the first phase-difference detection sub-pixel sl,
but may be incident onto a photodiode only in a second
phase-difference detection sub-pixel sr. In contrast, an optical
signal to be incident onto a second direction region AR of the
image pickup device 118, which is located off the optical axis
toward a second direction, may be incident onto a photodiode of a
first phase-difference detection sub-pixel sl, but may not reach a
photodiode of a second phase-difference detection sub-pixel sr.
[0098] Thus, as illustrated in FIG. 7B-3, in the front focus state,
in the first direction region AL, which is located off the optical
axis toward the first direction, the second phase-difference
detection signal may have a high magnitude (I), while the first
phase-difference detection signal may have a low magnitude (I). In
the second direction region AR, which is located off the optical
axis toward the second direction, the first phase-difference
detection signal may have a high magnitude (I), while the second
phase-difference detection signal may have a low magnitude (I). If
the second phase-difference detection signal of the first direction
region AL of the image pickup device 118, which is located off the
optical axis toward the first direction, is detected having a
magnitude (I) greater than or equal to a predetermined critical
level, the first phase-difference detection signal of the first
direction region AL is detected having a magnitude (I) less than
the predetermined critical level, the first phase-difference
detection signal in the second direction region AR of the image
pickup device 118, which is located off the optical axis toward the
second direction, is detected having a magnitude (I) greater than
or equal to the predetermined critical level, and the second
phase-difference detection signal in the second direction region is
detected having a magnitude (I) less than the predetermined
critical level, the phase-difference AF processing unit 630 may
determine that a current state is the front focus state.
[0099] In the back focus state, as illustrated in FIG. 7C-1, an
optical signal incident onto the image pickup device 118 through
the lens 111 is not focused on the center region of the
light-receiving surface of the image pickup device 118, and is
instead focused behind the light-receiving surface of the image
pickup device 118.
[0100] In the back focus state, as illustrated in FIG. 7C-2, an
optical signal to be incident onto the first direction region AL of
the image pickup device 118, which is located off the optical axis
toward a first direction, may be blocked by a mask layer of a
second phase-difference detection sub-pixel sr, thus being unable
to reach a photodiode of the second phase-difference detection
sub-pixel sr, but may be incident onto a photodiode only in a first
phase-difference detection sub-pixel sl. In contrast, an optical
signal to be incident onto the second direction region AR of the
image pickup device 118, which is located off the optical axis
toward a second direction, may be incident onto a photodiode of a
second phase-difference detection sub-pixel sr, but may not reach a
photodiode of a first phase-difference detection sub-pixel sl.
[0101] Thus, as illustrated in FIG. 7C-3, in the back focus state,
in the first direction region AL, which is located off the optical
axis toward the first direction, the first phase-difference
detection signal may have a high magnitude (I), while the second
phase-difference detection signal may have a low magnitude (I). In
the second direction region AR, which is located off the optical
axis toward the second direction, the second phase-difference
detection signal may have a high magnitude (I), while the first
phase-difference detection signal may have a low magnitude (I). If
the first phase-difference detection signal of the first direction
region AL of the image pickup device 118, which is located off the
optical axis toward the first direction, is detected to having a
magnitude (I) greater than or equal to a predetermined critical
level, the second phase-difference detection signal of the first
direction region AL is detected having a magnitude (I) less than
the predetermined critical level, the second phase-difference
detection signal in the second direction region AR of the image
pickup device 118, which is located off the optical axis toward the
second direction, is detected to having a magnitude (I) greater
than or equal to the predetermined critical level, and the first
phase-difference detection signal in the second direction region is
detected having a magnitude (I) less than the predetermined
critical level, the phase-difference AF processing unit 630 may
determine that a current state is the back focus state.
[0102] In an embodiment of the present invention, to determine
whether a current state is in the in-focus state, the
phase-difference AF processing unit 630 may calculate a correlation
value between the first and second phase-difference detection
signals. For example, correlation values between the first
phase-difference detection signals and the second phase-difference
detection signals of each of the pixels may be calculated. If a
correlation value in the center region of the image pickup device
118 is greater than or equal to a threshold value, the center
region of the image pickup device 118 is determined to be in the
in-focus state. Otherwise, the center region of the image pickup
device 118 may be determined to be an AF disable state.
[0103] The contrast AF processing unit 640 may perform
contrast-based AF using an image pickup signal processed by the
image pickup signal processing unit 620. The contrast AF processing
unit 640 may extract a high-frequency component of the image pickup
signal corresponding to a contrast component using a band path
filter. A predetermined process, for example, an integration
process, may be performed on the extracted contrast component. For
example, an integration of the contrast component may be performed
with respect to time. The contrast AF processing unit 640 may drive
the lens 111 to maximize the contrast component.
[0104] In an embodiment of the present invention, the contrast AF
processing unit 640 may perform contrast AF using a Y component,
i.e., a luminance component, of an image pickup signal converted to
a YCC signal.
[0105] The AF microcomputer 650 may generate a lens driving control
signal using a result value of phase-difference AF by the
phase-difference AF processing unit 630 and a result value of
contrast AF by the contrast AF processing unit 640, and may output
the lens driving control signal to the lens driving unit 112.
According to embodiments of the present invention, since whether a
current state is the in-focus state and a driving direction of the
lens may be determined by the phase-difference AF processing unit
630, it may be not necessary to detect contrast components with
respect to the entire driving range of the lens 111, and contrast
AF may be performed using only contrast components detected from
some regions. This contrast-based AF may be performed by the AF
microcomputer 650. Therefore, high-speed, precise AF may be
performed according to the above-described embodiments of the
present invention.
[0106] Although FIG. 6 illustrates an embodiment of the present
invention in which both phase-difference AF and contrast AF are
performed, the present invention is not limited thereto. In another
embodiment of the present invention, AF may be performed using only
a result of phase-difference AF by the phase-difference AF
processing unit 630.
[0107] The interpolation unit 660 interpolates an image pickup
signal generated by the image pickup device 118.
[0108] FIG. 8 is a diagram for explaining interpolation according
to embodiments of the present invention.
[0109] In current embodiments of the present invention, the image
pickup device 118 may have the same sub-pixel pattern over its
entire region. That is, each pixel of the image pickup device 118
may include a phase-difference detection sub-pixel S in the same
location. This structure enables interpolation of the entire region
of the image pickup device 118 using neighboring pixels of the same
pattern. Therefore, according to the current embodiments, uniform
interpolation may be guaranteed with the image pickup device 118
including the phase-difference detection pixels S.
[0110] FIG. 8A illustrates an example of interpolation of a red
sub-pixel R. The interpolation unit 660 acquires a green component
using image pickup signals of neighbor green sub-pixels G
neighboring the red sub-pixel R, and a blue component using image
pickup signals of blue sub-pixels B neighboring the red sub-pixel
R.
[0111] FIG. 8B illustrates an example of interpolation of a green
sub-pixel G. The interpolation unit 660 acquires a red component
using image pickup signals of red sub-pixels R neighboring the
green sub-pixel G, and a blue component using image pickup signals
of blue sub-pixels B neighboring the green sub-pixel G.
[0112] FIG. 8C illustrates an example of interpolation of a blue
sub-pixel B. The interpolation unit 660 acquires a red component
using image pickup signals of red sub-pixels R neighboring the blue
sub-pixel B, and a green component using image pickup signals of
green sub-pixels G neighbor the blue sub-pixel B.
[0113] FIG. 8D illustrates an example of interpolation of a
phase-difference detection sub-pixel S. The interpolation unit 660
acquires a red component using image pickup signals of red
sub-pixels R neighboring the phase-difference detection sub-pixel
S, a green component using image pickup signals of green sub-pixels
G neighboring the phase-difference detection sub-pixel S, and a
blue component from image pickup signals of blue sub-pixel B
neighboring the phase-difference detection sub-pixel S.
[0114] As illustrated in FIGS. 8A-8D, individual red sub-pixels R,
green sub-pixels G, blue sub-pixels B, and phase-difference
detection sub-pixels S may be uniformly interpolated using
neighboring sub-pixels of the same pattern.
[0115] Referring back to FIG. 6, the codec 670 may encode an image
pickup signal processed by the image pickup signal processing unit
620, according to a predetermined format, or may decode an image
file stored in, for example, the data storage unit 142 after being
encoded. The codec 670 may encode the image pickup signal according
to a JPEG standard, an MPEG standard, or the like, or may decode an
image signal in the image file.
[0116] FIG. 9 is a block diagram illustrating a configuration of
the phase-difference AF processing unit 630, according to an
embodiment of the present invention.
[0117] According to the current embodiment of the present
invention, the phase-difference AF processing unit 630 may include
a pixel selection unit 902, a buffer control unit 904, a buffer
906, a pre-processing unit 908, a subtraction unit 910, a detection
unit 912, an in-focus determination unit 914, and a defocus
processing unit 916.
[0118] The pixel selection unit 902 receives a phase-difference
detection signal extracted by the AF signal extraction unit 610 as
the first and second phase-difference detection signal from each
pixel, and stores the first and second phase-difference detection
signals in the buffer 906 via the buffer control unit 904. The
buffer control unit 904 corrects a time gap between the first and
second phase-difference detection signals caused from a difference
in location between imaging surfaces of first and second
phase-difference detection sub-pixels sl and sr. The pre-processing
unit 908 may process the first and second phase-difference
detection signals, for example, to eliminate noise, to adjust a
signal amplitude, and so that phase-difference information is
readily detectable at a later process. The subtraction unit 910
performs subtraction between the first and second phase-difference
detection signals to extract a difference between the first and
second phase-difference detection signals. The detection unit 912
quantitatively detects information of the difference between the
first and second phase-difference detection signals and calculates
a correlation level between the first and second phase-difference
detection signals. If the correlation level of the first and second
phase-difference detection signals from the center region of the
image pickup device 118, calculated by the detection unit 912, is
high, or if both the magnitudes of the first and second
phase-difference detection signals from the center region of the
image pickup device 118 are greater than or equal to a critical
level, the in-focus determination unit 914 may determine that a
current state is the in-focus state. If the in-focus determination
unit 914 determines that a current state is not the in-focus state,
the defocus processing unit 916 may determine whether the current
state is the front focus state or the back focus state. Whether in
the current state is the front focus state or the back focus state
may be determined as described with reference to FIGS.
7B-1-7C-3.
[0119] FIG. 10 is a flowchart illustrating an AF method according
to an embodiment of the present invention.
[0120] According to the current embodiment of the present
invention, the AF method may involve detecting the first and second
phase-difference detection signals from a center region of the
image pickup device 118 (S1002), determining whether the magnitudes
of the first and second phase-difference detection signals are
greater than or equal to a critical level (S1004), and determining
that a current state is the in-focus state (S1006). If either the
magnitude of the first or second phase-difference detection signal
is less than the critical level (S1004), the first and second
phase-difference detection signals from a peripheral region of the
image pickup device 118 toward a first direction from an optical
axis are detected (S1008). If the magnitude of the second
phase-difference detection signal is greater than or equal to the
critical level and the magnitude of the first phase-difference
detection signal is less than the critical level (S1010), the
current state is determined as the front focus state (S1012). If
the magnitude of the first phase-difference detection signal is
greater than or equal to the critical level and the magnitude of
the second phase-difference detection signal is less than the
critical level (S1014), the current state is determined as the back
focus state (S1016). If the current state is neither the front
focus state nor the back focus state, the current state is
determined as the AF disable state (S1018).
[0121] FIG. 11A illustrates an arrangement of a plurality of pixels
according to another embodiment of the present invention. FIG. 11B
illustrates light-receiving regions of phase-difference detection
sub-pixels sl1, sl2, sr1, and sr2. FIG. 11C illustrates shooting
pupils, and FIG. 11D is a diagram for describing phase-difference
AF operations according to focal distances.
[0122] According to the current embodiment of the present
invention, as illustrated in FIG. 11A, a plurality of pixels are
arranged in the image pickup device 118, each pixel including one
of first to fourth phase-difference detection sub-pixels sl1, sl2,
sr1, and sr2, and a plurality of light-receiving sub-pixels R, G,
and B. Pixels including first phase-difference detection sub-pixels
sl1 are referred to as first group pixels G1, pixels including
second phase-difference detection sub-pixels sr1 are referred to as
second group pixels G2, pixels including third phase-difference
detection sub-pixels sl2 are referred to as third group pixels G3,
and pixels including fourth phase-difference detection sub-pixels
sr2 are referred to as fourth group pixels G4.
[0123] As illustrated in FIG. 11B, a first phase-difference
detection sub-pixel sl1 may include a confined light-receiving
region 212a arranged biased to a first direction. A second
phase-difference detection sub-pixel sr1 may include a confined
light-receiving region 214a arranged biased to a second direction.
A third phase-difference detection sub-pixel sl2 may include a
confined light-receiving region 212b arranged biased to the first
direction. A fourth phase-difference detection sub-pixel sr2 may
include a confined light-receiving region 214b arranged biased to
the second direction. The confined light-receiving regions 212a,
214a, 212b, and 214b respectively of the first to fourth
phase-difference detection sub-pixels sl1, sr1, sl2, and sr2 may
form a shape extending along a column direction. As illustrated in
FIG. 11A, pluralities of the first group pixels G1, the second
group pixels G2, the third group pixels G3, and the fourth group
pixels G4 may each be consecutively arranged in the row direction
as a group, and the groups of the first group pixels G1, the second
group pixels G2, the third group pixels G3, and the fourth group
pixels G4 may alternate in the column direction.
[0124] According to an embodiment of the present invention, the
confined light-receiving regions 212a, 214a, 212b, and 214b may
form shooting pupils, as illustrated in FIG. 11C, in the image
pickup device 118. According to an embodiment of the present
invention, an image pickup signal may be generated from an optical
signal incident through a shooting pupil of a light-receiving
sub-pixel, and phase-difference AF may be performed with optical
signals incident through the shooting pupils of the first to fourth
phase-difference detection sub-pixels sl1, sr1, sl2, and sr2.
[0125] According to an embodiment of the present invention,
referring to FIG. 11D, in a first focal distance region FL1,
phase-difference AF may be performed using the first
phase-difference detection signal from a first phase-difference
detection sub-pixel sl1 and the second phase-difference detection
signal from a second phase-difference detection sub-pixel sr1, and
in a second focal distance region FL2, phase-difference AF may be
performed using a third phase-difference detection signal from a
third phase-difference detection sub-pixel sl2 and a fourth
phase-difference detection signal from a fourth phase-difference
sub-pixel sr2. The second focal distance region FL2 is a region in
which shorter focal distances than those in the first focal
distance region FL1 are defined.
[0126] In the first focal distance region FL1 where an optic angle
is relatively small, the magnitudes of the third and fourth
phase-difference detection signals output from respective third and
fourth phase-difference detection sub-pixels sl2 and sr2 with the
confined light-receiving regions each biased relatively much to the
first or second direction may be too small to be used for
phase-difference AF, while the magnitudes of the first and second
phase-difference detection signals output from respective first and
second phase-difference detection sub-pixels sl1 and sr1 with the
confined light-receiving regions each biased relatively little to
the first or second direction may be greater than or equal to a
predetermined level that is high enough for phase-difference AF. In
contrast, in the second focal distance region FL2 where an optic
angle is large, the magnitudes of the first and second
phase-difference detection signals output from respective first and
second phase-difference detection sub-pixels sl1 and sr1 with the
confined light-receiving regions each biased relatively little to
the first or second direction may be too small to be used for
phase-difference AF, while the magnitudes of the third and fourth
phase-difference detection signals output from respective third and
fourth phase-difference detection sub-pixels sl2 and sr2 with the
confined light-receiving regions each biased relatively much to the
first or second direction may be greater than or equal to the
predetermined level that is high enough for phase-difference
AF.
[0127] According to an embodiment of the present invention, in the
first focal distance region FL1, phase-difference AF may be
performed using the first and second phase-difference detection
signals, and in the second focal distance region FL2,
phase-difference AF may be performed using the third and fourth
phase-difference detection signals. The foregoing structure may
ensure high-performance phase-difference AF in all focal distance
ranges within the driving range of the lens 111. The first focal
distance region FL1 and the second focal distance region FL2 may be
defined to be consecutive regions with respect to a predetermined
threshold, or to overlap in a predetermined focal distance
region.
[0128] FIG. 12A illustrates an arrangement of a plurality of pixels
according to another embodiment of the present invention. FIG. 12B
illustrates light-receiving regions of phase-difference detection
sub-pixels sl, sl, st, and sb. FIG. 12C illustrates shooting
pupils.
[0129] According to the current embodiment of the present
invention, as illustrated in FIG. 12A, a plurality of pixels are
arranged in the image pickup device 118, each pixel including one
of first, second, fifth, and sixth phase-difference detection
sub-pixels sl, sr, st, and sb, and a plurality of light-receiving
sub-pixels R, G, and B.
[0130] Pixels including first phase-difference detection sub-pixels
sl are referred to as first group pixels G1, pixels including
second phase-difference detection sub-pixels sr are referred to as
second group pixels G2, pixels including fifth phase-difference
detection sub-pixels st are referred to as fifth group pixels G5,
and pixels including sixth phase-difference detection sub-pixels sb
are referred to as sixth group pixels G6.
[0131] As illustrated in FIG. 12B, a first phase-difference
detection sub-pixel sl may include a confined light-receiving
region 212 arranged biased to a first direction. A second
phase-difference detection sub-pixel sr may include a confined
light-receiving region 214 arranged biased to a second direction. A
fifth phase-difference detection sub-pixel st may include a
confined light-receiving region 1202 arranged biased to a third
direction that is parallel to a column direction perpendicular to a
row direction. A sixth phase-difference detection sub-pixel sb may
include a confined light-receiving region 1204 arranged biased to a
fourth direction that is parallel to the column direction and
opposite to the third direction. The confined light-receiving
regions 212 and 214 of the first and second phase-difference
detection sub-pixels sl and sr may form a shape extending along the
column direction. The confined light-receiving regions 1202 and
1204 of the fifth and sixth phase-difference detection sub-pixels
st and sb may form a shape extending along the column
direction.
[0132] As illustrated in FIG. 12A, the first group pixels 01 and
the second group pixels G2 may be arranged in a first region A1,
and the fifth group pixels G5 and the second group pixels G6 may be
arranged in a second region A2. The first region A1 and the second
region A2 may alternate, as illustrated in FIG. 12A.
[0133] In the first region A1, pluralities of the first group
pixels 01 and the second group pixels G2 may each be consecutively
arranged in a row direction as a group, and the groups of the first
group pixels 01 and the second group pixels G2 may alternate in the
column direction. In the second region A1, pluralities of the fifth
group pixels G5 and the sixth group pixels G6 may each be
consecutively arranged in the column direction, and the groups the
fifth group pixels G5 and the sixth group pixels G6 may alternate
in the row direction.
[0134] The arrangements of the first region A1 and the second
region A2 are not limited to the embodiment of FIG. 12A, and may be
varied in different ways. Widths of the first region A1 and the
second region A2 may be larger than those illustrated in FIG. 12A.
In another embodiment of the present invention, the first region A1
and the second region A2 may alternate, wherein each region
includes a plurality of pixels in four columns. In another
embodiment of the present invention, the first region A1 and the
second region A2 may be arranged in a checkerboard pattern.
[0135] According to an embodiment of the present invention, the
confined light-receiving regions 212, 214, 1202, and 1204 may form
shooting pupils, as illustrated in FIG. 12C, in the image pickup
device 118. According to an embodiment of the present invention, an
image pickup signal may be generated from an optical signal
incident through a shooting pupil of a light-receiving sub-pixel,
and phase-difference AF may be performed using optical signals
incident through the shooting pupils of the first, second, fifth,
and sixth phase-difference detection sub-pixels sl, sr, st, and
sb.
[0136] If, in a region of the image pickup device 118 located
biased to the third direction away from an optical axis, a sixth
phase-difference signal output from a sixth phase-difference
detection sub-pixel sb is detected to be greater than or equal to a
predetermined critical level and a fifth phase-difference detection
signal output from a fifth phase-difference detection sub-pixel st
is detected to be less than the predetermined critical level, a
current state may be determined to be in the front focus state. If,
in the region of the image pickup device 118 located biased to the
third direction away from the optical axis, the fifth
phase-difference detection signal is detected to be greater than or
equal to the predetermined critical level and the sixth
phase-difference detection signal is detected to be less than the
predetermined critical level, the current state may be determined
to be in a back focus state.
[0137] In the current embodiment in which a combination of shooting
pupils of first and second phase-difference detection sub-pixels sl
and sr biased along a row direction and shooting pupils of the
fifth and sixth phase-difference detection sub-pixels st and sb
biased along a column direction, high-performance phase-difference
AF may be secured even when no phase difference characteristic in
either the row or column direction is detected from incident
optical signals.
[0138] FIG. 13A illustrates an arrangement of a plurality of pixels
according to an embodiment of the present invention. FIG. 13B
illustrates light-receiving regions of phase-difference detection
sub-pixels sl1, sr1, sl2, sr2, sl3, and sr3. FIG. 13C is a diagram
for describing arrangements of the phase-difference detection
sub-pixels sl1, sr1, sl2, sr2, sl3, and sr3 according to regions of
the image pickup device 118.
[0139] According to the current embodiment of the present
invention, as illustrated in FIG. 13A, a plurality of pixels are
arranged in the image pickup device 118, each pixel including one
of first phase-difference detection sub-pixels sl1, sl2, and sl3
and second phase-difference detection sub-pixels sr1, sr2, and sr3,
and a plurality of light-receiving sub-pixels R, G, and B. Pixels
including first phase-difference detection sub-pixels sl1, sl2, or
sl3 are referred to as first group pixels G1, and pixels including
second phase-difference detection sub-pixels sr1, sr2, or sr3 are
referred to as second group pixels G2.
[0140] According to the current embodiment of the present
invention, degrees of bias of confined light-receiving regions of
first and second phase-difference detection sub-pixels sl1, sl2,
sl3, sr1, sr2, sr3 may vary according to different regions of the
image pickup device 118. As illustrated in FIG. 13C, in regions A,
B, and C of the image pickup device 118, which respectively
correspond to a center region of the image pickup device 118, a
region biased to a first direction from an optical axis of the
image pickup device 118, and a region biased to a second direction
from the optical axis of the image pickup device 118, the confined
light-receiving regions of first phase-difference detection
sub-pixels sl1, sl2, and sl3 may have different arrangements, and
those of second phase-difference detection sub-pixels sr1, sr2, and
sr3 may have different arrangements.
[0141] In the region B biased to the first direction from the
center of the image pickup device 118, a confined light-receiving
region 212b of a first phase-difference detection sub-pixel sl2 may
be arranged in the center of the first phase-difference detection
sub-pixel sl2 or biased relatively less to the first direction, and
a confined light-receiving region 214b of a second phase-difference
detection sub-pixel sr2 may be arranged biased to the second
direction. In an embodiment of the present invention, the further
the second phase-difference detection sub-pixel sr2 is away from
the center of the image pickup device 118 in the first direction,
the further the confined light-receiving region 214b of a second
phase-difference detection sub-pixel sr2 may be biased to the
second direction.
[0142] In the region C biased to the second direction from the
center of the image pickup device 118, a confined light-receiving
region 212c of a first phase-difference detection sub-pixel sl3 may
be arranged biased to the second direction, and a confined
light-receiving region 214b of a second phase-difference detection
sub-pixel sr3 may be arranged in the center of the second
phase-difference detection sub-pixel sr3 or biased relatively less
to the second direction. In an embodiment of the present invention,
the further the first phase-difference detection sub-pixel sl3 is
away from the center of the image pickup device 118 in the second
direction, the further the confined light-receiving region 212c of
a first phase-difference detection sub-pixel sl3 may be biased to
the first direction.
[0143] In the region A, which is in the center of the center of the
image pickup device 118, a confined light-receiving region 212a of
a first phase-difference detection sub-pixel sl1 may be arranged
biased to the first direction, and a confined light-receiving
region 214a of a second phase-difference detection sub-pixel sr2
may be arranged biased to the second direction. The confined
light-receiving region 212a of a first phase-difference detection
sub-pixel sl1 in the region A may be arranged biased relatively
less to the first direction compared to the confined
light-receiving region 212c of a first phase-difference detection
sub-pixel sl3 in the region C. The confined light-receiving region
214a of a second phase-difference detection sub-pixel sr1 in the
region A may be arranged biased relatively less to the second
direction compared to the confined light-receiving region 214b of a
second phase-difference detection sub-pixel sr2 in the region
B.
[0144] According to the current embodiment of the present
invention, confined light-receiving regions of phase-difference
detection sub-pixels may have different arrangements in different
regions of the image pickup device 118 according to incident
characteristics of optical signals in each region of the image
pickup device 118. This may lead to high-performance
phase-difference AF.
[0145] The embodiments of FIGS. 13A to 13C may apply to the fifth
group pixels G5 and the sixth group pixels G6 in FIGS. 12A to 12C.
That is, the confined light-receiving regions of the fifth group
pixels G5 may be arranged in the centers of corresponding
phase-difference detection sub-pixels if the phase-difference
detection sub-pixels are located in a region of the image pickup
device 118 in the third direction from the optical axis, or may be
arranged biased to the third direction if the phase-difference
detection sub-pixels are located in a region of the image pickup
device 118 in the fourth direction from the optical axis. The
confined light-receiving regions of the sixth group pixels G6 may
be arranged in the centers of corresponding phase-difference
detection sub-pixels if the phase-difference detection sub-pixels
are located in a region of the image pickup device 118 in the
fourth direction from the optical axis, or may be arranged biased
to the fourth direction if the phase-difference detection
sub-pixels are located in a region of the image pickup device 118
in the third direction from the optical axis.
[0146] The AF method according to embodiments of the present
invention can also be embodied as computer readable codes on a
computer readable recording medium. The computer readable recording
medium is any data storage device that can store data that can be
thereafter read by a computer system.
[0147] An example of the computer readable recording medium
includes flash memory, or the like.
[0148] The device described herein may comprise a processor, a
memory for storing program data and executing it, a permanent
storage such as a disk drive, a communications port for handling
communications with external devices, and user interface devices,
including a display, keys, etc. When software modules are involved,
these software modules may be stored as program instructions or
computer readable codes executable on the processor on a
computer-readable media such as read-only memory (ROM),
random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks,
and optical data storage devices. The computer readable recording
medium can also be distributed over network coupled computer
systems so that the computer readable code is stored and executed
in a distributed fashion. This media can be read by the computer,
stored in the memory, and executed by the processor.
[0149] All references, including publications, patent applications,
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0150] For the purposes of promoting an understanding of the
principles of the invention, reference has been made to the
preferred embodiments illustrated in the drawings, and specific
language has been used to describe these embodiments. However, no
limitation of the scope of the invention is intended by this
specific language, and the invention should be construed to
encompass all embodiments that would normally occur to one of
ordinary skill in the art.
[0151] The present invention may be described in terms of
functional block components and various processing steps. Such
functional blocks may be realized by any number of hardware and/or
software components configured to perform the specified functions.
For example, the present invention may employ various integrated
circuit components, e.g., memory elements, processing elements,
logic elements, look-up tables, and the like, which may carry out a
variety of functions under the control of one or more
microprocessors or other control devices. Similarly, where the
elements of the present invention are implemented using software
programming or software elements the invention may be implemented
with any programming or scripting language such as C, C++, Java,
assembler, or the like, with the various algorithms being
implemented with any combination of data structures, objects,
processes, routines or other programming elements. Functional
aspects may be implemented in algorithms that execute on one or
more processors. Furthermore, the present invention could employ
any number of conventional techniques for electronics
configuration, signal processing and/or control, data processing,
and the like. The words "mechanism" and "element" are used broadly
and are not limited to mechanical or physical embodiments, but can
include software routines in conjunction with processors, etc.
[0152] The particular implementations shown and described herein
are illustrative examples of the invention and are not intended to
otherwise limit the scope of the invention in any way. For the sake
of brevity, conventional electronics, control systems, software
development and other functional aspects of the systems (and
components of the individual operating components of the systems)
may not be described in detail. Furthermore, the connecting lines,
or connectors shown in the various figures presented are intended
to represent exemplary functional relationships and/or physical or
logical couplings between the various elements. It should be noted
that many alternative or additional functional relationships,
physical connections or logical connections may be present in a
practical device. Moreover, no item or component is essential to
the practice of the invention unless the element is specifically
described as "essential" or "critical".
[0153] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural. Furthermore, recitation of ranges
of values herein are merely intended to serve as a shorthand method
of referring individually to each separate value falling within the
range, unless otherwise indicated herein, and each separate value
is incorporated into the specification as if it were individually
recited herein. Finally, the steps of all methods described herein
can be performed in any suitable order unless otherwise indicated
herein or otherwise clearly contradicted by context. The use of any
and all examples, or exemplary language (e.g., "such as") provided
herein, is intended merely to better illuminate the invention and
does not pose a limitation on the scope of the invention unless
otherwise claimed. Numerous modifications and adaptations will be
readily apparent to those skilled in this art without departing
from the spirit and scope of the present invention.
[0154] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *